#include <stdio.h>
#include <string.h>
#include <ctype.h>

char zd(char x[], char w[]) {
	int i, j = 0, max = 0, flag = 0;
	char temp[20] = "";
	for (i = 0; i <= strlen(x); i++) {
		if (tolower(x[i]) >= 'a' && tolower(x[i]) <= 'z') {
			temp[j++] = x[i];
		} else {
			j = 0;
			if (max < strlen(temp)) {
				max = strlen(temp);
				strcpy(w, temp);
			}
			strcpy(temp, "");
		}
	}
}

int main() {
	char str[80], word[20];
	gets(str);
	zd(str, word);
	puts(word);
}
